The cylindrical tube of a spray pump has a radius $R,$ one end of which has $n$ fine holes, each of radius $r.$ If the speed of the liquid in the tube is $v,$ the speed of the ejection of the liquid through the holes is:

An ideal fluid flows through a pipe of circular cross-section made of two sections with diameters $2.5$ cm and $3.75$ cm. The ratio of the velocities in the two pipes is:
1. $9:4$
2. $3:2$
3. $\sqrt{3}:\sqrt{2}$
4. $\sqrt{2}:\sqrt{3}$

Water enters through end $A$ with a speed $v_1$ and leaves through end $B$ with a speed $v_2$ of a cylindrical tube AB. The tube is always completely filled with water. In case I the tube is horizontal, in case II it is vertical with the end $A$ upward and in case III it is vertical with the end $B$ upward. We have $v_1=v_2$ for:
1. case I
2. case II
3. case III
4. each one